The present invention relates to a process and apparatus for treating a material with a fluid, and in particular, for changing the chemical and/or physical nature of that material under controlled pressure and temperature conditions. Of particular interest is a process and apparatus for treating a tobacco material with a fluid at pressures greater than ambient pressures.
Popular smoking articles, such as cigarettes, have a substantially cylindrical rod-shaped structure and include a charge of smokable material, such as shreds or strands of tobacco material (i.e., in cut filler form), surrounded by a paper wrapper, thereby forming a tobacco material rod. It has become desirable to manufacture a cigarette having a cylindrical filter element aligned in an end-to-end relationship with the tobacco material rod. Typically, a filter element includes cellulose acetate tow circumscribed by plug wrap, and is attached to the tobacco material rod using a circumscribing tipping material.
Tobacco material undergoes various processing steps prior to the time that it is used for cigarette manufacture. Oftentimes, a tobacco material is chemically and/or physically altered to modify its flavor and smoking characteristics.
In certain circumstances, it may be desirable to selectively remove substances, such as nicotine, from a tobacco material. Various processes directed toward removing nicotine from tobacco material have been proposed. Many of such types of processes are discussed in European Patent Application Nos. 280817 and 323699, and in U.S. Pat. Nos. 4,153,063 to Roselius et al. and 4,744,375 to Denier et al.
In other circumstances it may be desirable to increase the filling capacity of a tobacco material. In particular, it may be desirable to decrease the density of an aged tobacco material by expanding the tobacco material thereby reducing the weight of the tobacco material employed in the manufacture of each cigarette. Many so-called expansion processes for increasing the filling capacity of tobacco material are set forth in U.S. Pat. Nos. 3,524,451 to Fredrickson; 3,524,452 to Moser et al; 3,683,937 to Fredrickson et al; 4,235,250 to Utsch; 4,791,942 to Rickett et al; 4,561,453 to Rothchild; and 4,531,529 to White et al.
It would be desirable to provide a process and apparatus for efficiently and effectively altering the chemical and/or physical nature of a material, such as a tobacco material, wherein a continual flow of material can be continuously contacted with a treatment fluid at pressures significantly above ambient pressure.